Electronic manometer



April 19, 1960 A. J. STOKES ETAL ELECTRONIC MANOMETER Filed May 6, 1955 INVENTOILS APT/ U2 J2 STOKES Pezoeezc w. RUTER,JR.

a tented Apr. 19, 1960 ELECTRONIC MAN OMETER Arthur J. Stokes, Hudson, and Frederic W. Renter, IL,

Cleveland, Ohio, assignors to The Victoreen Instrument Company, Cleveland, Ohio Application May 6, 1955, Serial No. 506,534

9 Claims. (Cl. 324-43) This invention relates to pressure measuring devices and more particularly to a device which enables the measurement very accurately of small variations in pressure.

It frequently becomes desirable to measure small variations in pressure and, depending upon where the pressure is to be measured, there are sometimes difliculties in taking the measurement without an extremely complicated mechanism. For instance it may be desirable to provide a certain apparatus which has thereima certain pressure, the maintenance of that pressure being necessaryto determine its operation. It may be that if the pres,- sure of such apparatus should fall below a predetermined minimum that its installation would result in the subsequent inoperativeness of the device or might cause premature operation which would be extremely dangerous.

By our present invention we are able to incorporate a pressure sensitive device in the apparatus, which device is extremely small and adds a minimum amount of weight and by means of which the pressure in the device may be determined by attaching an ancillary apparatus thereto.

Another use of such a device is for automatic control of a process which is pressure sensitive.

Briefly we have discovered that by utilizing a corona regulator tube which regulates according to the pressure in the tube, in a device that the pressure in the device may be determined by measuring the point of regulation and particularly to the point of voltage regulation.

In thedrawings the figure is a diagram of a circuit as used in conjunction with a regulator tube according to our invention.

The regulator tube which is of the so-called corona regulator type may be connected to any device wherein the pressure is to be measured. In one particular instance it is connected into a container which houses certain parts of the apparatus in such manner that as pressure in the housing varies the pressure in the tube varies accordingly. In this instance thetube may become a permanent part of the apparatus. Measurements of pressure may be made by connecting the reader to the regulator tube.

Such a tube may be very small as shown in the single figure of the drawing wherein a tube drawn to a scale of 1:1 is illustrated in this case, a fragment of the housing 10 is illustrated, the cathode of the tube may comprise a metal cylinder 11 having a flange 12, the base 13 of which is secured in an aperture in the wall 10. The anode 15 is supported coaxially of the cathode by a glass head 16. The end of the anode projects beyond the bead to provide a convenient terminal.

A source of voltage supply is provided for the corona regulator. This voltage may be any conventional voltage source which will supply suflicient voltage to maintain a corona discharge at the desired current in the corona regulator as well as for the remainder of the apparatus. The voltage source has the positive terminal connected to the anode of the corona regulator tube through a series resistance 21. The cathode of the regulator tube is connected to the negative side of the voltage source through a resistance composed of a fixed resistor 25 and a variable resistor 26.

Means is provided to automatically establish the required voltage applied to the corona tube and which will maintain a predetermined current level through the corona tube. In addition this apparatus measures the voltage, which voltage may be interpreted in terms of gas pressure.

A tube 20, which may be but is not necessarily, a triode, has an anode connected to the positive side of the power supply through the resistance 21. The cathode of this tube is connected to. the negative side of the power supply through a reference voltage device which may be a voltage regulator tube 22, the anode of which is connected to the cathode of the tube 20 and the cathode of which is connected to the negative side of the power supp This has now provided a parallel path for current after passing through the common resistor 21; one of the paths is through tubes 20-22, and may be considered as a variable resistance path and the other through the corona regulator tube. The total of the currents through these paths determines the voltage drop between the voltage supply and the corona tube and therefore determines the voltage supply to the corona tube.

Since the current versus voltage relationship of the corona tube is a direct function of the gas pressure in the tube, a reading of the voltage required to maintain a corona discharge with a predetermined magnitude of current, can be interpreted in terms of gas pressure. Therefore the regulating device must present to the corona tube exactly that voltage which is required to produce the desired discharge for any value of gas pressure which may exist.

The series resistance 2526 in the corona tube circuit is such that the magnitude of the corona current will determine the voltage drop across it. This voltage drop, plus or minus a reference voltage, is applied as a grid bias to the tube 20 which is connected as a shunt regulator tube and controls the amount of current flowing through the variable resistance path which includes the tube 20.

The grid bias voltage, which is the voltage appearing across the resistance 25-26 and reference voltage tube 22, is applied to the grid of the tube 20 through the resistor 30 which in conjunction with the condenser 31 comprises a decoupling or anti-hunt circuit that eliminates the effects of transients. Normally this results in a negative bias on the grid but under conditions of gross maladjustment it could be positive.

The resistor 26, being adjustable, enables the voltage at the corona tube to be adjusted to provide any value of constant current at which the pressure measurements should be made, by adjusting the bias and controlling the operating point of the tube 20.

Having established the voltage necessary to maintain a predetermined current level through the corona tube it now remains to measure that voltage which may berinterpreted in terms of pressure. To measure this voltage any conventional means may be used. It is conventient, however, to measure only a portion of the voltage which thus provides a suppressed zero for the meter itself resulting in an expanded scale with its concomitant increased ac-- curacy and readability. To this end We prefer to read the voltage across the tube 20 at the anode and the cathode.

The measuring instrumentality includes a meter 40 which having one end connected to the cathode and the 3 other end connected through the resistor Means is provided for adjusting the sensitivity of the meter which comprises a shunt variable resistor 42 across the meter. The zero point of the meter may be adjusted by providing an adjustable leakage path tominus B of the power supply through the iesistor 43' and variable resistor 44. 7

A resistance 46 is provided from the positive side of the B supply to the anode of the reference tube 22 and supplies a'current path for the reference tube to maintain adequate current through the tube and maintain voltage regulation regardless of current drawn by the shunt regulator tube.

Although we have illustrated and described a specific form of reader'for determining the amount of voltage applied to the corona regulator tube the description is for the purpose of explanation rather than limitation. For instance the circuit illustrates and describes a shunt regulator type of circuit for the corona tube and with the basic concepts as explained it will be apparent to those versed in the art that a serious regulator type of circuit could be used without departing from the spirit or scope of the invention as defined by the appended claim.

We claim:

1. An electronic manometer for. measuring gas pressure in a vessel comprising a corona voltage regulator tube of small gas volume as compared to the vessel, said regulator tube being built into and becoming a part of said vessel, means for supplying voltage to said voltage regulator tube at a value suflicient to maintain a corona discharge therein with a constant current comprising a source of voltage, a voltage regulator for said'source, and means for deriving a control voltage from said corona regulator tube and applying it to said voltage regulator to control said voltage regulator, and indicating means for indicating the value ofthe voltage applied to the corona regulator tube in terms of gas pressure.

2. A device as described in claim 1 wherein the pressure indicating means is a voltage measuring'means for measuring the voltage across the voltage regulator.

3. An electronic manometer comprisinga corona voltage regulator tube having its interior connected to and subjected to changes in pressure of the source to be measured, means for supplying voltage at a constant current'to said corona regulator tube comprising a source of voltage supply, regulator means in shunt with said corona regulator tube across said voltage supply and including a vacuum tube in series with means for provid- 41 to the-anode.

ing a fixed reference voltage, and means to control the shunting characteristics ot said combination including a resistance in series with said voltage reference means for deriving a bias voltage for said vacuum tube. V

4. A device as described in claim 3 wherein means is provided to measure the voltage applied to the corona regulator tube which comprises indicator means connected across the terminals of the vacuum tube in series with voltage dropping means.

5. A device for measuring fluid pressure comprising a corona voltage regulator tube constructed to have an internal pressure which varies with the pressure to be measured, voltage supply means connected to the corona regulator tube to apply a'voltage to thecorona regulator tube, said voltage supply nieans including means regulating said voltage to maintain a predetermined current to the tube which causes the tube to operate in the corona region, and means connected to said voltage supply means to indicate the value of said voltage applied to the corona regulator tube.

6. The device of claim 5, wherein said voltage regulating meanscomprises means coupled to the corona regulator tube and responsive to the magnitude of the current therein to control the voltage applied to the corona regulator tube. p

7. A pressure measuring device comprising a corona regulator tube having a housing connected 'to have its interior subjected to a pressure being measured, voltage supply means connected to the corona regulator tube to applya voltage to the corona regulator tube, said voltage supply means including means rcgulatingsaid voltage to maintain a predetermined current to the corona regulator tube, and a voltage measuring device connected to said voltage supply means to indicate the value of the voltage applied to the corona'regulator tube. 7 '8. A device as claimed in claim 7 having means connected to the corona'regulator tube for deriving'a potential therefrom andconnected to said regulating means to control the latters voltage regulating operation.

1 '9. 'A pressure measuring device comprising a corona regulator tube which has a pair of electrodes and is connected. to have its interior subjected to a pressure being regulated, a pair of voltage supply terminals, common resistance means connected between one of said voltage supply terminals and one of said electrodes of the corona regulator tube, second resistance means connected between theother electrode of the corona regulator tube and the other voltage supply terminal so that the potential across said second resistance means varies with the current to the corona regulator tube, an electron discharge device having a control electrode and a voltage regulator tube connected in series with each other between said common resistance means and said other voltage supply terminal, third resistance means connected be tween said other electrode of the corona regulator tube and the control electrode of said electrode discharge device to apply said potential to said control electrode, and voltage measuring means connected across said electron discharge device to measure the voltage across said elec tron discharge device as an indication of thevoltage across the corona regulator tube. 7

References Cited in the file of this patent UNITED STATES PATENTS Schafer May 10,1921

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,933,676 April 19, 1960 Column 3, line 21 for serious" read series Signed and sealed this 27th day of September 1960,

SEAL) Attest:

KARL HQ AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents 

